Abstract
In this paper, we consider a cognitive radio network that consists of one cognitive base station (CBS) and multiple cognitive users (CUs) in the presence of an eavesdropper. In the cognitive radio network, CBS first detects whether there is spectrum hole through spectrum sensing and then communicates with CUs over the detected spectrum hole. Due to the broadcast nature of wireless transmission, the eavesdropper can overhear the cognitive transmissions between CBS and CUs and attempts to decode its overheard signals for interception purpose. In order to effectively defend against the eavesdropping attack, we propose a multiuser scheduling scheme for cognitive transmissions, where a CU with the highest instantaneous capacity to CBS is selected and scheduled to communicate with CBS. We analyze the security-reliability trade-off performance of proposed multiuser scheduling scheme for cognitive transmissions with the imperfect spectrum sensing over Rayleigh fading channels, where the security and reliability are evaluated in terms of the intercept probability and the outage probability, respectively. Numerical results illustrate that as the intercept probability requirement loosens, the outage probability of proposed multiuser scheduling scheme decreases accordingly, showing the trade-off between security and reliability. In addition, as the number of CUs increases, numerical intercept probability and outage probability of the multiuser scheduling scheme significantly improve, implying the security and reliability benefits through multiuser scheduling.
Highlights
Cognitive radio (CR) is emerging as a means to improve the spectrum resource utilization and allows unlicensed users to access the licensed spectrum in an opportunistic way [1,2,3]
Most of radio spectrum is already licensed to particular wireless systems, e.g., the very high frequency (VHF) band from 174 to 216 MHz is allocated to broadcast television systems in North America, the ultra-high frequency (UHF) band from 880 to 915 MHz is allocated to the Global System for Mobile Communications (GSM), and so on
We investigate the security-reliability trade-off for cognitive radio transmissions with imperfect spectrum sensing, where mutual interference between primary and cognitive users should be taken in account in characterizing the SRT performance
Summary
Cognitive radio (CR) is emerging as a means to improve the spectrum resource utilization and allows unlicensed users ( called secondary user or cognitive user) to access the licensed spectrum in an opportunistic way [1,2,3]. We investigate the security-reliability trade-off for cognitive radio transmissions with imperfect spectrum sensing, where mutual interference between primary and cognitive users should be taken in account in characterizing the SRT performance. Numerical results show that with an increasing number of CUs, the SRT performance of cognitive radio transmissions significantly improves, showing the advantage of proposed multiuser scheduling scheme against eavesdropping attack. Cw jhCBS‐Eav j2 P s αjhPBS‐Eavj2PP þ ð5Þ where subscript ‘w’ denotes the wiretap channel from CBS to Eav. Without loss of generality, we consider that CUi is selected as the best user to access the detected spectrum hole. Substituting Equations 19 and 20 into Equation 18, we can obtain the closed-form outage probability expression of direct transmission scheme as 1⁄4 π0
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